/*
 *
 * author:dustin
 * email:dushaobindoudou@gmail.com
 *
 * 调配用的，不同浏览器加载不同的css，不同的js
 *
 * 不赞同所有用到的js同时都加载过来，要针对不同浏览器器写不同的js，yui的进化版
 *
 * 队列 [{url:"js资源地址",success:"成功回调",error:"出错回调"}]
 *
 * todo:加载错误通知，需要修正
 *
 * todo:delete all loaded script
 *
 * todo:DomReady：beginLoad
 *
 * todo:Delay image、css
 *
 *
 */

!(function(win){
    var doc = win.document;
    var head = doc.getElementsByTagName("head")[0];
    var a = navigator.userAgent.toLowerCase();
    var b = {
        IE: {
            is: /msie/.test(a),
            ver: (/msie (\d\.\d)/.exec(a)) && (/msie (\d\.\d)/.exec(a)[1])
        },
        OPERA: /opera/.test(a),
        MOZ: /gecko/.test(a) && !/(compatible|webkit)/.test(a),
        SAFARI: !/chrome\/([\d.]*)/.test(a) && /\/([\d.]*) safari/.test(a),
        CHROME: /chrome\/([\d.]*)/.test(a),
        IPAD: /\(ipad/i.test(a),
        IPHONE: /\(iphone/i.test(a),
        ITOUCH: /\(itouch/i.test(a),
        MOBILE: /mobile/i.test(a)
    };
    var addDomReadyCallback = (function(){
        // Everything that has to do with properly supporting our document ready event. Brought over from the most awesome jQuery. 
        var userAgent = navigator.userAgent.toLowerCase();
        // Figure out what browser is being used
        var browser = {
            version: (userAgent.match(/.+(?:rv|it|ra|ie)[\/: ]([\d.]+)/) || [])[1],
            safari: /webkit/.test(userAgent),
            opera: /opera/.test(userAgent),
            msie: (/msie/.test(userAgent)) && (!/opera/.test(userAgent)),
            mozilla: (/mozilla/.test(userAgent)) && (!/(compatible|webkit)/.test(userAgent))
        };
        var readyBound = false;
        var isReady = false;
        var readyList = [];
        // Handle when the DOM is ready
        function domReady(){
            // Make sure that the DOM is not already loaded
            if (!isReady) {
                // Remember that the DOM is ready
                isReady = true;
                if (readyList) {
                    for (var fn = 0; fn < readyList.length; fn++) {
                        readyList[fn].call(window, []);
                    }
                    readyList = [];
                }
            }
        };
        
        // From Simon Willison. A safe way to fire onload w/o screwing up everyone else.
        function addLoadEvent(func){
            var oldonload = window.onload;
            if (typeof window.onload != 'function') {
                window.onload = func;
            }
            else {
                window.onload = function(){
                    if (oldonload) {
                        oldonload();
                    }
                    func();
                }
            }
        };
        // does the heavy work of working through the browsers idiosyncracies (let's call them that) to hook onload.
        function bindReady(){
            if (readyBound) {
                return;
            }
            readyBound = true;
            // Mozilla, Opera (see further below for it) and webkit nightlies currently support this event
            if (document.addEventListener && !browser.opera) {
                // Use the handy event callback
                document.addEventListener("DOMContentLoaded", domReady, false);
            }
            // If IE is used and is not in a frame
            // Continually check to see if the document is ready
            if (browser.msie && window == top) 
                (function(){
                    if (isReady) 
                        return;
                    try {
                        // If IE is used, use the trick by Diego Perini
                        // http://javascript.nwbox.com/IEContentLoaded/
                        document.documentElement.doScroll("left");
                    } 
                    catch (error) {
                        setTimeout(arguments.callee, 0);
                        return;
                    }
                    // and execute any waiting functions
                    domReady();
                })();
            if (browser.opera) {
                document.addEventListener("DOMContentLoaded", function(){
                    if (isReady) 
                        return;
                    for (var i = 0; i < document.styleSheets.length; i++) 
                        if (document.styleSheets[i].disabled) {
                            setTimeout(arguments.callee, 0);
                            return;
                        }
                    // and execute any waiting functions
                    domReady();
                }, false);
            }
            
            if (browser.safari) {
                var numStyles;
                (function(){
                    if (isReady) 
                        return;
                    if (document.readyState != "loaded" && document.readyState != "complete") {
                        setTimeout(arguments.callee, 0);
                        return;
                    }
                    if (numStyles === undefined) {
                        var links = document.getElementsByTagName("link");
                        for (var i = 0; i < links.length; i++) {
                            if (links[i].getAttribute('rel') == 'stylesheet') {
                                numStyles++;
                            }
                        }
                        var styles = document.getElementsByTagName("style");
                        numStyles += styles.length;
                    }
                    if (document.styleSheets.length != numStyles) {
                        setTimeout(arguments.callee, 0);
                        return;
                    }
                    
                    // and execute any waiting functions
                    domReady();
                })();
            }
            // A fallback to window.onload, that will always work
            addLoadEvent(domReady);
        };
        bindReady();
        // This is the public function that people can use to hook up ready.
        return function(fn, args){
            // Attach the listeners
            bindReady();
            // If the DOM is already ready
            if (isReady) {
                // Execute the function immediately
                fn.call(window, []);
            }
            else {
                // Add the function to the wait list
                readyList.push(function(){
                    return fn.call(window, []);
                });
            }
        };
    })();
    
    var Loader = function(quene, async){
        this.quene = quene || [];
        this.async = async;
        this.allLoaded = function(){
        };
        this.queneCount = this.quene.length;
        this.loaded = 0;
    }
    
    Loader.prototype = {
        constructor: Loader,
        init: function(callback){
            var that = this;
            if (callback) {
                this.allLoaded = callback;
            }
            addDomReadyCallback(function(){
                that.loading.apply(that, []);
            });
        },
        createScript: function(url, callback){
            var script = doc.createElement("script");
            var complete = false;
            callback = callback ||
            function(){
            }
            if (b.IE.is) {
                if (parseFloat(b.IE.ver) > 8) {
                    script.onload = callback;
                }
                else {
                    script.onreadystatechange = function(){
                        if (!complete && (!this.readyState || this.readyState === 'complete' || (this.readyState === 'loaded'))) {
                            complete = true;
                            callback();
                            script.onreadystatechange = null;
                        }
                    }
                }
            }
            else {
                script.onload = callback;
            }
            script["type"] = "text/javascript";
            script["charset"] = "utf-8";
            script["src"] = url;
            script["async"] = this.async;
            return script;
        },
        createCSS: function(url, callback){
            var lk = doc.createElement("link");
            var complete = false;
            callback = callback ||
            function(){
            }
            if (b.IE.is) {
                if (parseFloat(b.IE.ver) > 8) {
                    lk.onload = callback;
                }
                else {
                    lk.onreadystatechange = function(){
                        if (!complete && (!this.readyState || this.readyState === 'complete' || (this.readyState === 'loaded'))) {
                            complete = true;
                            callback();
                            script.onreadystatechange = null;
                        }
                    }
                }
            }
            else {
                lk.onload = callback;
            }
            lk["type"] = "text/css";
            lk["rel"] = "stylesheet";
            lk["charset"] = "utf-8";
            lk["href"] = url;
            return lk;
        },
        appendScript: function(one){
            var that = this;
            if (!one) {
                return;
            }
            //var head = doc.getElementsByTagName("head")[0];
            head.appendChild(this.createScript(one.url, function(){
                that.loaded++;
                if (that.loaded >= that.queneCount) {
                    that.allLoaded();
                }
                if (one.callback) {
                    one.callback();
                }
            }));
        },
        appendCss: function(one){
            var that = this;
            if (!one) {
                return;
            }
            head.appendChild(this.createCss(one.url, function(){
                that.loaded++;
                if (that.loaded >= that.queneCount) {
                    that.allLoaded();
                }
                if (one.callback) {
                    one.callback();
                }
            }));
        },
        appendAsync: function(one){
            var that = this;
            if (!one) {
                return;
            }
            var fl;
            switch (one.type) {
                case "css":
                    fl = this.createCSS(one.url, function(){
                        that.loaded++;
                        if (that.loaded >= that.queneCount) {
                            that.allLoaded();
                        }
                        if (one.callback) 
                            one.callback();
                        that.appendAsync(that.quene.shift());
                    });
                    break;
                case "js":
                    fl = this.createScript(one.url, function(){
                        that.loaded++;
                        if (that.loaded >= that.queneCount) {
                            that.allLoaded();
                        }
                        if (one.callback) 
                            one.callback();
                        that.appendAsync(that.quene.shift());
                    });
                    break;
                default:
                    break;
            }
            head.appendChild(fl);
        },
        loading: function(){
            var i = 0, len = this.quene.length, that = this;
            if (this.async) {
                for (; i < len; i++) {
                    var one = this.quene.shift();
                    if (one) {
                        switch (one.type) {
                            case "css":
                                that.appendCss();
                                break;
                            case "js":
                                that.appendScript(one);
                                break;
                            default:
                                break;
                        }
                    }
                }
            }
            else {
                var one = this.quene.shift();
                that.appendAsync(one);
            }
        }
    }
    win.Loader = Loader;
})(window)
